Lucy Gardner has cut her commuting costs by two thirds since last year, when her fuel bill was £240 a month to drive between her home in Manchester and job in Liverpool. And then there was the wear and tear on her 20-year-old Toyota Corolla.

Like many commuters, Lucy, 28, had tried public transport. But the train added another hour to the return journey and wasn’t much cheaper. The bus was £80 a month but took five hours.

As a last resort, Lucy started taking the car. “I soon realised that driving to work alone wasn’t sustainable,” says Lucy, assistant curator at Liverpool’s Walker Art Gallery. “It was an 80-mile round trip, which was also really boring.”

Lucy finally found a way to slash her travel costs last April – by filling the empty seats in her car with other commuters.

She’s not alone. Sir Bob Kerslake, the new head of the Civil Service, and the new Cabinet Secretary Jeremy Heywood share a chaufeur-driven car every morning for the commute to Whitehall.

Through the liftshare.com website, Lucy located three other people already in a car share, and who were making the same commute. She asked to join them and now alternates driving with car owners Rob Scott, 28, and Tom McDonald, 29. Fourth commuter Maisie Platts, 27, chips in £4-£5 a day for fuel.

“And there are other benefits – you can have a chat, or a rest if you’re not driving. You can also have a good whinge about work, so when you get home you’ve got it out of your system.”

Lucy is one of a growing number of commuters using the internet to find others to share their journey to work, slashing travel costs in the process. High fuel prices and insurance premiums, plus soaring train fares, mean many are finding it harder than ever to afford the daily commute. More are looking at car sharing as a cheaper – and greener – alternative.

Liftshare is the UK’s biggest car-sharing network and is seeing a surge in interest. Almost 64,000 people joined in 2010. In 2011, this rose to 71,000 – or about 6,000 new members per month. This means it’s on track to hit 500,000 members by April.

According to Liftshare, which is a social enterprise, the typical commuter who car-shares every day saves about £800 a year, but many save much more. Meanwhile, 91 per cent of car commuting is single occupancy.

Members must be over 18 to register on the site, which is free to use. They input the trips they’d like to share, with details of times and destination, and search for suitable matches. People without a car can inquire about lifts in their area and contribute to fuel.

Cecilia Bromley-Martin, Liftshare’s head of communications, says rising motoring costs have had a definite impact on the popularity of the site.

“Petrol prices are double what they were in 1999 and many people have realised that driving to work on their own is just not viable. Some of our members are saving well over £2,000 a year just for making the effort to find people to share with.”

She adds that a number of businesses now pay to use Liftshare’s systems to run their own car-sharing scheme, including Jaguar Land Rover, Sky and Scottish Power.

She says: “Employers are catching on to the benefits, which include solving parking issues and boosting their green credentials.”

Tom, a research scientist at the University of Liverpool who car-shares with Lucy, reckons he saves at least £1,200 in diesel per year for his Renault Clio. There’s also £350 on servicing and repairs and £100 on insurance due to cutting his mileage from 22,000 to 10,000.

Tom says: “I was a bit apprehensive at first, I wasn’t sure what was involved. After all, you’re sitting in a car with someone you don’t know. But now I wouldn’t want to drive to work on my own again.

“Car sharing has saved me a fair bit of money, but there are also environmental benefits and the social aspect of it. We get on really well, and with four of us there’s usually plenty to chat about.”

Car-sharing sites don’t only cater for commuters – they’re used for just about any journey, from students needing a lift home from university to the weekly shop.

Of course, not every online match will result in a successful car share for commuters. Pick up and drop off times and locations need to be agreed and stuck to as much as possible. For example, it might be tricky for someone who’s unable to guarantee the time they leave work. However, it is possible to mix and match to increase flexibility, such as sharing a lift to work with one person and the return journey with another.

There are also safety aspects to consider when getting into a vehicle with a stranger. Liftshare members are encouraged to use the site’s messaging system and meet in a public place before committing.

Safety was a concern for both Suzanne Phinan, 43, and Clare Howard, 48, who met through Liftshare last November. They now alternate driving the 88-mile round trip from their homes in Dunfermline to Ninewells Hospital in Dundee, where they both work. They estimate this saves them each at least £100 a month.

Suzanne, a theatre nurse, says: “A few people contacted me but when Clare got in touch I was relieved – it’s easier when it’s another woman, plus we had lots in common. We’re the same kind of age and both have kids.

“We emailed and arranged to meet in reception after work, just to be on the safe side. But we got on so well we decided to start car-sharing the following week. As well as saving money I really enjoy having company on the journey. It’s been a brilliant success.”

Scott Williams, a 34-year-old commercial manager, is also pleased with his car-share, which he’s been running for four years, from Cambridge to Canary Wharf. He finds people to share with through BlaBlaCar.com, and drives in three days a week, sharing his car with up to five others who work in the same area. He saves about £175 a month, and precious time.

“Despite a few issues, such as getting people to let me know their plans for the week ahead and make their contributions, I do enjoy the company and to be honest, I’d be lost without them all now,” he says.

The Association of British Insurers states that an individual’s policy isn’t affected as long as no profit is made. Passengers can contribute towards the car’s running costs providing a vehicle seats eight passengers or fewer. If in doubt, call your insurer.

Tips for finding a car share

- Don’t wait for someone to contact you, carry out regular searches for new members and make contact with those who might be suitable as soon as possible.

- If a car-sharer doesn’t drive, there’s a Savings Calculator on the Liftshare site to work out a suggested contribution to costs.

- Ensure you can stick to agreed travel times, to avoid making someone late for work, or delay them getting home.

- Arrange a week’s trial period before committing.

- Check driving licences or ID to ensure you’re meeting the right person and arrange to meet potential sharers in a public place first. Inform someone about the journey details.